1. Field of the Invention
This invention relates to a photovoltaic system using reflected solar rays of the surroundings to dispose of snow, frost, ice, and the like. This invention relates in particular to photovoltaic systems having means to efficiently use the reflected solar ray from the surroundings of the photovoltaic systems, whether direct or diffused, for snow, frost, and ice disposal and methods therefor.
2. Description of Related Art
At present the most sold and profitable photovoltaic systems for continental climates such as Canada, must be operative year around in sites far remote from civilization, roads, and electrical sources. For this reason, reliability in electricity supply derived from said photovoltaic systems is a must, coupled with a minimum maintenance requirement and absence of combustibles requirement.
The main cause for power failure of these photovoltaic systems is due to snow, frost, and ice covering up the cells. Indeed, even a partial obstruction suffices to create high energy losses. For instance, 2 cm of snow over photovoltaic systems decrease the energy output by 90%. A few millimeters suffice to reduce the output by half. Snow covering of the cells also has a cumulative effect, insofar as the non-removed snow induces accumulation of future snows and to that extent reduces the sun rays able to reach the photovoltaic cells and which might be used, for instance, to heat-up these photovoltaic systems.
At present, in order to avoid snow accumulation, the photovoltaic systems are placed at an angle which is high with respect to the horizontal; they are even vertically placed. This, however, diminishes the energy output without eliminating the snow being blown or the glazed frost and the hoar-frost laid by frosted fog, mist, and haze. In winter, from October to April, the energy loss due to a vertical positioning of the photovoltaic systems, instead of an inclination of 45.degree. or 60.degree., is greater than 15%, mainly due to the fact that the system collects less diffused radiation of the cloudy mass. In summer, 30% to 40% of the solar radiation is not collected.
A search has revealed the following patents all aiming at overcoming this problem of snow and ice:
Masakatsu et al teach in JP 53-72487 dated Jun. 27, 1978, a solar cell unit that reduces the effect of the snow and ice, by providing a transparent panel having small friction resistance and thermal transfer rate in front of the solar cell module constituted with solar cells contained in a transparent material and a removably mounted black panel having a good thermal absorption at the back of the solar cells. Thus the sun rays are moving through the transparent panel to hit the cells and therebetween said cells, the black panel.
K. Haensel teaches in DE 2936764 filed Mar. 19, 1981, incorporating a heating foil controlled by a switch, to melt ice and snow.
F. Cuevas teaches in BE-889735 filed Nov. 16, 1981, a dual sided solar panel for incident and reflected light, having series connected photoelectric cells illuminated from both sides, for improved conversion efficiency.
G. Bicher and R. Pfeil teach in DE 2814243 filed Oct. 11, 1979, a temperature sensor on dark absorption surface metal pilate embedded in insulating material, for a multiple storage solar energy powered heating system. This sensor detects wind, rain, snow, and the like.
M. Kitanishi teaches in JP 62-285477 dated Dec. 11, 1987, a reflecting plate to increase efficiency in generating electricity.
Sasaya et al, teach in JP 62-18074 dated Jan. 27, 197, an auxiliary heat generating apparatus to facilitate snow removal.
Yagi et al, teach in JP 60-235442 dated Nov. 22, 1985, to reverse the direction of the electric current to thaw when necessary.
Y. Inoue teaches in JP 59-231877 dated Dec. 26, 1984, an electrically heated system comprising a transparent hollow glass.
Kanema et al, teach in JP 62-122181 dated Jun. 3, 1987, waterproofing of the peripheral part of a module.
Yabe et al, in JP 56-73478 dated Jun. 18, 1981, teach a special structure for a panel surface of solar cells.
None of the above patents taken alone or in combination, teach Applicant's invention.